In normal-weight subjects, the effects of a high carbohydrate (HI-CHO) vs high fat (HI-FAT) diet/meal on lipoprotein lipase (LPL) responsiveness in adipose tissue (at) or skeletal muscle (sm)will predict weight stability vs weight gain over 5 yr and in obese subjects, the effects of a HI-CHO vs HI-FAT diet/ meal on tissue-specific LPL responsiveness will predict weight stability of the obese weight vs additional weight gain over 5 yr.